#include <REGX52.H>
void Delay(unsigned int xms)	
{
	unsigned char i, j;
	while(xms--)
	{
		i = 2;
		j = 239;
		do
		{
			while (--j);
		} while (--i);
	  
	}
}

void main()
{
	unsigned char num=0;
	P2=~0X01;
	
	while(1)
	{
		
		if(P3_1==0)
		{
			Delay(20);
			while(P3_1==0);
			Delay(20);
			num++;
			if(num>=8)
			{
				num=0;
			}
			P2=~(0x01<<num);
			
		}
		if(P3_0==0)
		{
			Delay(20);
			while(P3_0==0);
			Delay(20);
			
			if(0==num)
			{
				num=8;
			}
			num--;
			P2=~(0x01<<num);
		}
		
	}
}